Tester for plastic deformation and elastic deformation of tested materials



April 9, 1963 SMALL ET AL 3,084,538

TESTER FOR PLASTIC DEFORMATION AND ELASTIC DEFORMATION OF TESTED MATERIALS Filed May 12, 1960 1/0 94 :ELE| L law 1151a 36 HZ 83 PLASTIC DEfflR/IAT/OA/ INVENTORS L Lou/s SMALL BY Ho WARD SMALL A TTOPNEVS EI-A 5 TIC DEFORMA TION Patented Apr. 9, 1963 tics TESTER FOR PLASTIC DEFORMATION AND ELASTIC DEFGRMATION F TESTED MA- TERIALS Louis Small and Howard Small, both of 8110 Concord, Huntingdon Woods, Mich. Filed May 12, 1960, Ser. No. 28,582 2 Claims. (Cl. 7383) This invention relates to a testing apparatus for materials having the character of undergoing plastic or permanent deformation and elastic or impermanent deformation under load.

Conventional hardness testing apparatus measures the plastic deformation, but for many materials and applications it is desirable to measure both the plastic deformation and the elastic deformation. The present invention is particularly designed to utilize a conventional hardness testing apparatus and to incorporate therewith a novel attachment structure whereby the apparatus can be made to measure plastic deformation and elastic deformation as separate identities.

One object of the invention is to provide an apparatus of the above novel character which has a relatively low manufacturing cost.

A further object of the invention is to provide an attachment of the above character which can be readily installed on conventional hardness testers.

Other objects of this invention will appear in the following description and appended claims, reference being had to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

In the drawings:

FIG. 1 is a semi-schematic view showing the major components of a hardness tester having the invention incorporated therewith.

FIG. 2 is an enlarged sectional view taken through a test piece showing the character of a penetrator-produced depression before and after removal of the major load.

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also, it is to be underestood that the phraseology or terminology employed herein is for the purpose of description and not of limitation.

Referring to the drawings, and particularly FIG. 1, there is shown a tester including a housing '10 having the rear wall '12, top wall 14, upper frontal wall 16, rearwardly directed ledge-like wall 18, recessed frontal wall 20, upwardly facing lower wall 22, and lower frontal wall 24.

The work undergoing test is shown at 26 and is adapted to rest on the anvil or support 28, said support being carried on a vertical screw 30 which is adapted to reciprocate up and down by a manual turning of nut 32, said nut having the manually graspable handles 34 thereon to facilitate the turning operation. The hardness testing operation is effected by the application of a major load onto the penetrator 36, said penetrator being fixedly carried on the lower portion of a floatable platform structure 38, and the major load being applied from a beam 40.

Beam 40 is pivotally mounted at 42 and is utilized in combination with a second beam 41 fulcrurned at 43. Beam 41 is provided at its free end with a ball socket structure 44 for suspending the weight hanger rod I means 46. The weight hanger rod means carries a platform '48 which serves to support the major load 50.

In order to provide an orderly and controlled slow application of the major load onto the penetrator 36 there is provided a dashpot structure including the dashpot housing 52 and piston 54. The piston is provided with a piston rod 56 which is suitably connected with a bell crank 58 having a fulcrum at 60. The lever carries a beam-engaging roller 62 at its upper end, and the pivot 60 mounts an external crank or operating handle 64. By manual rotation of crank 64 in the clockwise direction the bell crank 58 can be rotated about the axis 60 so as to swing the roller 62 away from the underside of extension 45 carried by beam 41. The weight of major load 50 tends to maintain beam 41 in engagement with the roller, particularly because of the retarding action of the dashpot piston 54. Air or other fluid is contained within the contained space 66 below piston 54, and a manually adjustable needle 68 may be provided to control the escape of fluid from space 66 into the line 70 which leads to the area above the piston. By suitably adjusting needle 66 the rate of escape of fluid into line 70 can be controlled so as to thereby control the rate of movement of the piston rod 56 and roller 62. By this arrangement a slow application of the major load can be effected so as to prevent erratic penetrator action on the test piece 26.

The actual transfer of the major load onto the penetrator takes place through beam 40, said beam having a pin or shaft 47 connected therewith so as to register with a notch structure 49 formed in beam 41. By this arrangement the clockwise rotation of handle 64 is effective to initially depress beam 41 and to thereafter transfer the weight of the major load 50 onto the beam 40 via the notch-pin arrangement at 49, 47. The beam 40 then transfers the load to the penetrator. The method and mechanism for load application is per se not a feature of the present invention, and the drawings therefore do not show the transfer mechanisms in detail. The features of these mechanisms are detailed in co-pending application, Serial No. 725,374, filed March 31, 1958, now Patent No. 2,986,030.

In order to apply the major load from beam 40 onto the penetrator there may be employed a block 72 having knife edges at its upper and lower ends. The upper knife edge seats in a notch formed in the beam 40, and the lower knife edge seats in a notch formed in the spindle 74. Spindle 74 is suitably connected with a rectangular plate 76 as by means of threading, bolting or the like as at 78. Each corner of plate 76 connects with a vertical post 80, and each of the vertical posts in turn connects with a corner portion of the aforementioned platform 38. In the illustrated embodiment each of members 38 and '76 is four inches by six inches by inch, and there are four corner posts, each five inches long and one inch square in cross-section. The assembly of elements 38, 80 and 76 constitutes a unitary framework 81.

The illustrated platform 38 is provided with three vertical bores, each serving to slidably support a freely moving pin or probe 82. Each pin may be provided With an enlarged upper end portion 84 to retain it from dropping out of the bore in platform 38. Only two of the pins 82 are visible in the drawings, the third pin lying out of the plane of the paper. Preferably the three pins are spaced equally from the axis of penetrator 36, both radially and circumferentially.

The three pins 82 serve to support a disc 86 which is located beneath the plunger 88 of a conventional dial indicator 90. The dial indicator is preferably supported on the platform 38, as by means of a bracket 92. For

convenience of illustration the drawings show a serpentinelike bracket construction butin practice a bracket formed as a bridge-like structure is preferred because of the improved rigidity which it offers to the dial indicator.

The dial indicator '90 is intended to measure the elastic deformation of the test piece, i.e., the ability of the test piece material to recover its shape after removal of the major load therefrom. In order to measure the plastic or permanent deformation of the test piece there is provided a dial indicator 94 suitably mounted on the upper wall 14 of the tester housing as by means of the L-shaped bracket 96. This dial indicator is provided with a plunger 98 which engages the small lever 100 fulcrumed at 102. Lever 100 is engaged by a pin or stem 104 which extends from the spindle 74 freely through a bore in block 72.

In operation of the illustrated tester the minor load is applied onto the test piece 26 (to move the penetrator through any surface imperfections therein) by manually elevating anvil 28. This operation is effected by manslally rotating the nut 32 via handles 34.

As the anvil 28 is elevated the Weight of framework 81 and beam is applied onto the test piece, and the test piece raises this weight upwardly so as to move the stern 104 against the underside of lever 100. By this action the lever 100 causes an upward movement of the plunger 98 which is recorded on the dial 106 of the indicator 94. Manual rotation of the nut 32 is continued until a predetermined deflection is observed on dial 106 of the indicator. In the usual arrangement this deflection is three revolutions of the indicator needle, and each revolution of the needle is denoted by a counter on the indicator dial. The needle deflection on dial 106 records the application of the minor load onto the test piece, said minor load serving to move the penetrator into the work piece surface a suflicient distance to overcome the effect of surface imperfections.

Each of the dial indicators 90 and 94 is preferably provided with a movable bezel as indicated by numerals 108 and 110 in the drawings. The purpose of these bezels is to reset the indicator dials to zero needle positions after load application. During application of the minor load the pins 82 will move upwardly relative to the platform 38 so as to provide a deflection of the needle in dial indicator 90. This needle deflection has no significance insofar as the present invention is concerned.

The major load is applied by manual clockwise rotation of handle 64, which action serves to apply the load of weights onto the beam '41, thence onto beam 40, and

thence onto the block 72 and spindle 74. The spindle transfers the downwardly acting force onto the framework 81 and thence onto the .penetrator 36. There will thus be a penetration of the member 36 into the test piece 26 which will cause a deflection of the needle on dial indicator 94. In this connection it will be appreciated that the dial indicator 94 is provided with the conventional internal loading springs for maintaining the plunger 98 in a position engaged with the lever 100 during the downward travel of spindle 74 and pin 104. I

After application of the major load the bezel 108 s preferably operated to set indicator 90 in the zero POSI- tion. The major load is then removed and the hardness or permanent deformation characteristic of the test piece is read from dial indicator 94. Removing the major load before reading indicator 94 relieves any strains produced in the machine elements during application of the major load and isolates the permanent deformation from the elastic deformation. In the illustrated arrangement removal of the major load is effected by a manual turning of the handle 64 in a counterclockwise position (to its illustrated position). It will be appreciated that a suitable check valve arrangement is provided in piston 54 to permit a quick return of the fluid from above the piston to the space 66 therebelow so as to permit the desired motion of the crank handle.

After removal of the major load the permanent deformation is read on the dial 106 and the elastic deformation is read from dial indicator 90. In measuring the elastic deformation of the test piece we are in effect comparing the position of the pins '82 relative to the penetrator 36 before and after removal of the major load. As previously noted, the bezel 108 for dial indicator is turned to give a zero reading before removal of the major load. During removal of the major load the penetrator 36 moves upwardly relative to the pins 82 and test piece surface 83, but the pins maintain their positions relative to surface 83. The upward movement of penetrator 36 moves the housing of dial indicator 90 upwardly, but the plunger 88 maintains its position on disk 86 (because of the internal springing Within the indicator housing). Therefore the needle of indicator 90 records the movement of penetrator 36' relative to pins 82 occurring after removal of the major load. This movement serves as an indication of the elastic deformation of the test piece material.

FIG. 2 illustrates the characteristics measured by the two dial indicators 90 and 94. :In the left portion of the figure the penetrator 36 is shown to an enlarged scale in the position which it takes before removal of the major lload. As there shown the depression 112 is relatively deep and is produced by plastic or permanent deformation plus elastic or impermanent deformation of the test piece 26. The right portion of the figure shows the condition of depression 112 after removal of the major load on penetrator 36. The difference in depth of the depression before and after removal of the major load is a measure of the elastic deformation characteristic of the test piece, i.e. its ability to elastically recover its original shape after removal of a predetermined major load. This elastic deformation characteristic is measured by the dial indicator 90, and the permanent deformation is measured by indicator 94.

It has been previously stated that in operation of the tester the bezel 108 for dial indicator 90 can be set to a zero position before removal of the major load. This procedure is advantageous in that it permits the elastic recovery characteristic of the test piece to be read directly from the dial. However, it is not essential to reset the bezel 108 to the zero position after removal of the major load. Thus, in some instances it may be desirable to merely note the dial reading for =dial 90 before removal of the major load and compare this reading with the reading obtained after removal of the major load. The difference between the two readings is a measure of the elastic recovery characteristic of the test piece material.

As previously noted, the drawings herein are semischematic in character, and in actual practice the tester is equipped with various auxiliary features of construction for accuracy of results. In this connection the tester is provided with various different mechanisms for applying and controlling the major load, together with features of adjustment and parts interchangeability such as are employed to vary the magnitude of the major load and the character of the penetrator in accordance with the different conventional scales, test materials, and test piece surface character. Certain desirable features of construction are shown in issued U.S. Patent 2,726,540 and copending'patent application Serial No. 725,374, filed March 31, 1958.

The primary feature of the present invention resides in the provision of the elastic deformation measuring apparatus depicted at 81, 82 and 90. It will be seen that this apparatus can be incorporated into a conventional hardness tester without substantial parts redesign or alterationof existing structure. This case of adaptability of the attachment structure is of material importance when the device is to be supplied to users having conventional hardness testing equipment at their command.

It will be appreciated that various modifications, rearrangements, and changes in parts configuration could be resorted to without departing from the spirit of the invention as set forth in the appended claims.

We claim:

1. A tester comprising a vertically traveling test piece supporting anvil; means for raising and lowering said anvil; a spindle structure positioned above the anvil at a substantial distance therefrom; a frame carried on the lower portion of said spindle, said frame defining a platform positioned adjacent the anvil but spaced therefrom; a test piece penetrator carried on said platform and extending toward the anvil; a plurality of freely moving pins slidably carried in said platform and in engagement with a test piece supported on the anvil whereby they will remain in a fixed position during platform movement; a dial indicator positioned within the framework and sup ported thereby; a first movable operating plunger for said dial indicator; disk means between the pins and the plunger for translating platform movement into first plunger movement; at second dial indicator having a second operating plunger; a lever for actuating said second plunger; means between the spindle and the lever for actuating said lever in response to up-and-down movement of said spindle; and means for applying a major load onto said spindle.

2. The combination comprising a tester housing; a Work-supporting anvil; means journalled in the housing for raising and lowering said anvil; a spindle arranged above the anvil for up-and-down movement relative to the housing; a first horizontal plate carried on the lower portion of the spindle; a second horizontal plate positioned below said first plate and constituting a platform; post means interconnecting said plates so as to cooperate therewith in forming a framework; a penetrator carried by the platform for engagement with a test piece supported on the anvil; a plurality of pins freely journalled in the platform for relative up-and-down movement with respect to the platform on movement of the platform; a disc resting on the upper ends of the pins; a dial indicator positioned with. in the framework and fixedly secured thereto; and a vertically movable plunger for the dial indicator engaged with the disc.

References Cited in the file of this patent UNITED STATES PATENTS 1,408,554 Widney Mar. 7, 1922 1,516,208 Rockwell Nov. 18, 1924 1,770,046 Shore July 8, 1930 2,329,827 Clark Sept. 21, 1943 2,759,353 Roberts Aug. 21, 1956 OTHER REFERENCES Williams: Indentation Hardness Testers, Instruments, vol. 11, pages 204-206. (Copy in Div. 36.) 

1. A TESTER COMPRISING A VERTICALLY TRAVELING TEST PIECE SUPPORTING ANVIL; MEANS FOR RAISING AND LOWERING SAID ANVIL; A SPINDLE STRUCTURE POSITIONED ABOVE THE ANVIL AT A SUBSTANTIAL DISTANCE THEREFROM; A FRAME CARRIED ON THE LOWER PORTION OF SAID SPINDLE, SAID FRAME DEFINING A PLATFORM POSITIONED ADJACENT THE ANVIL BUT SPACED THEREFROM; A TEST PIECE PENETRATOR CARRIED ON SAID PLATFORM AND EXTENDING TOWARD THE ANVIL; A PLURALITY OF FREELY MOVING PINS SLIDABLY CARRIED IN SAID PLATFORM AND IN ENGAGEMENT WITH A TEST PIECE SUPPORTED ON THE ANVIL WHEREBY THEY WILL REMAIN IN A FIXED POSITION DURING PLATFORM MOVEMENT; A DIAL INDICATOR POSITIONED WITHIN THE FRAMEWORK AND SUPPORTED THEREBY; A FIRST MOVABLE OPERATING PLUNGER FOR SAID DIAL INDICATOR; DISK MEANS BETWEEN THE PINS AND THE PLUNGER FOR TRANSLATING PLATFORM MOVEMENT INTO FIRST PLUNGER MOVEMENT; A SECOND DIAL INDICATOR HAVING A SECOND OPERATING PLUNGER; A LEVER FOR ACTUATING SAID SECOND PLUNGER; MEANS BETWEEN THE SPINDLE AND THE LEVER FOR ACTUATING SAID LEVER 